1. Field of the Invention
The present invention relates to a method for automatically setting an injection molding speed condition in an injection molding machine which moves an injection plunger thereby injecting melted material to a mold cavity of a mold.
2. Description of the Related Art
Conventionally, skilled workers set an injection molding speed condition by supposing a flow of melted material in a mold cavity of an injection mold on a basis of a shape of the mold cavity of the injection mold and the melted material, and by checking a finish of a trially-molded product.
Japanese Patent Application KOKAI Publication No. 61-69423 discloses that an amount of pressurized fluid, which is supplied to a hydraulic pressure cylinder of a hydraulic pressure unit for moving an injection plunger of an injection molding machine, is controlled on a basis of an injection material filling pressure sensed by a material pressure sensor provided in a mold cavity of the injection mold, so that injection material filling pressure (injection mold expanding force) is set to be a predetermined reference value. However, an object of such a conventional invention is that the injection mold is not be subjected to extra internal stress by extra injection material filling pressure. The above prior art does not specify how the injection speed (condition of the injection molding speed) of the melted material in an injection process, from a start of the injection process to an end of the injection process, is specifically set.
Moreover, Japanese Utility Model Application KOKAI Publication No. 58-86327 discloses that speed of melted material injected from an injection molding machine is controlled such that a plurality of resin pressure sensors provided in a mold cavity of an injection mold sense a predetermined pressure. However, in even this prior art, it is not specified how the injection speed (condition of an injection molding speed) of the melted material of an injection process, from a start of the injection process to an end of the injection process, is specifically set.
In setting the injection molding speed by the skilled workers, if a shape of a mold cavity of an injection mold is complicated, the number of trial-moldings is increased, so that it takes much time to set the injection molding speed.
The present invention has been derived from the above-mentioned circumstances. An object of the present invention is to provide a method for automatically setting an injection molding speed in an injection molding machine, which can easily set the injection molding speed with a small number of trial-moldings.